Method and apparatus to equalize tension in two or more strands



.Dec. 26, 1967 N- E. KLEIN 3,359,716

METHOD AND APPARATUS TO EQUALIZE TENSION IN TWO OR MORE STRANDS lled Feb 23 1965 2 Sheets-Sheet l FIG. 2-

INVENTOR.

NORMAN E. KLEIN ATTORNEY 1967 N. E. KLEIN 3,

METHOD AND APPARATUS TO EQUALIZE TENSION IN TWO OR MORE STRANDS Flled Feb 23 1965 2 Sheets-Sheet 2.

INVENTOR. NORMAN E; KLEIN ATTORNEY United States Patent 3,359,716 METHGD AND APPARATUS T0 EQUALIZE TENSION IN TWO OR MORE STRANDS Norman E. Klein, Spartanburg, S.C., assignor to Deer-ing Milliken Research Corporation, Spartanburg, S.C., a

corporation of Delaware Filed Feb. 23, 1965, Ser. No. 434,465 12 Claims. (Cl. 57106) ABSTRACT OF THE DISCLOSURE Method and apparatus to equalize tension in two or more strands being plied by mechanically interconnecting a plurality of capstans to transfer the unbalanced force from one capstan to the other capstans to equalize the tension in all the strands being plied.

This invention relates to methods and apparatus for the maintenance of strand tensions and more specifically to strand tension equalizing methods and apparatus which are suitable for use in conjunction with apparatus for twisting two or more strands together to form a plied construction.

In the forming of plied yarns of symmetrical construction it is necessary that the tension in each yarn of a group be made substantially the same if maximum strength is to be achieved. For this reason, tension equalizers have been developed whereby an increase in tension of any one of the yarns in a group actuates the tension equalizer to modify the tension of all yarns and thereby restore them to substantial tension equality.

Strand tension control systems, heretofore known, have employed individual tension regulators in control devices, the regulators operating as individual units, one per strand, to control tension to a preset level. Each of these individual units must be adjusted to a particular tension, the tension being that tension to which every other unit in the group is adjusted. In this way, by having each unit control to a particular level, equalization is achieved. However, if the average tension level to which an individual control unit is adjusted, is exceeded, the whole array of two or more units will have to be readjusted. A second deficiency in these so called individual tension control units is that these units provide only partial leveling action and they are as a rule affected by the varying coefiicients of friction of the yarns.

The prime prerequisite in the preparation of a strong cord or yarn is to tension each strand in that cord or yarn equally, so that it will take up its proper share of the load and not become overloaded before its neighbor. The need for strand tension equalizing becomes all the more critical in high modulus strand materials since stretch elongation here is much less and therefore the small stretch deformations of such cords have critical bearing on how the individual strand assumes its share of the load. The need for a flexible unitary device which will provide equalization of tension among a plurality of strands rather than separate individual strand control units that control to a particular level will therefore be readily appreciated.

Accordingly, it is an object of this invention to provide an improved process for maintaining strand tensions in a fixed ratio.

It is another object of this invention to provide an improved process for equalizing tensions in a strand plying operation.

It is still another object of this invention to provide an improved process for maintaining a preselected tension in a single running strand.

It is a further object of this invention to provide a process for strand tension equalizations to a degree of accuracy effected only by the residual friction of the moving parts in the control system.

It is an additional object of this invention to provide a strand tension equalizing device which is substantially unaffected by the coefficient of friction of the strand in contact with the surfaces of the equalizing device.

It is still another object of this invention to provide a unitary apparatus for equalizing tensions among a plurality of strands wherein the apparatus is adaptable for use with any combination of a plurality of strands.

In accordance with the present invention, a method has now been discovered for equalizing strand tensions by correcting any existing tension unbalance by subjecting at least one low tension strand to a winding operation While subjecting at least one high tension strand to an unwinding operation. In the event that tensions are being equalized prior to a two strand plying operation, the degree of winding to which the low tension strand is subjected will be exactly equal to the degree of unwinding to which the high tension strand is subjected. In order to determine the degree of winding or unwinding which is necessary, each strand is caused to be able to produce a torquing force, the strand which produces the greatest torquing force being the strand which is subjected to the greatest unwinding operation. It should be understood that when all strand tensions are equalized, the strands merely slip on the surfaces of revolution.

It has also been discovered that this method of equalizing strand tensions may be carried out by means of a tension equalizing apparatus comprising a plurality of surfaces of revolution each of which are provided with a means for receiving a strand in a direction substantially parallel to the axis of rotation of the surface of revolution and a means for ejecting said strand in a direction substantially perpendicular to the axis of rotation of said surface of revolution, that is to say in a direction tangential to the periphery of the surface of revolution. The strand receiving member and the strand ejecting member are preferably a common orifice. However, it should be understood that pin members, pigtail guide members and the like may also be employed for receiving and ejecting the strand. The term surface of revolution as employed herein is meant to define any member having the ability to effect a winding or an unwinding operation. Surfaces of revolution which are especially suitable for purposes of this invention are cylindrical members such as for instance, capstans and the like. When a plurality of capstans are employed, each of the capstans are preferably provided With an orifice cutting through an upper edge of said capstan whereby a lever arm is formed when a strand is laced through said orifice, each of said capstans being coupled to a mechanical torque transmission system whereby a torque produced by a tension unbalance at one capstan will result in the transfer of the force to such other capstans as will result in an equalization of tension. The mechanical torque transmission system may be a system such as for instance a cog belt, a sprocket and chain assembly or a gear train. Where the tension equalizing apparatus employs two capstans for equalizing tensions in a two ply cord or yarn, the forces at the surfaces of the capstans are equal, through the transmission of equal torques and a tension unbalance at one capstan, will result in the transfer of all of the force to the other capstan thereby resulting in an equalization of tension. The transmission of equal torques may be easily provided by joining each of the capstans to a shaft. Where, however, there are more than two capstans, there must be a differential gear outlet to each capstan position to provide access to that torquing force. The number of differentials will be equal to the number 3 of strands to be handled minus two. The number of strands is equal, of course, to the number of capstans in use.

It should be understood that the apparatus of this invention is also suitable for use in maintaining a constant tension on a single running strand. The single running strand is conveniently maintained at a preselected tension by placing that preselected tension on one surface of revolution whereby the tension of the running strand being received and ejected by a second surface of revolution is equalized with the preselected tension. The equalization is produced, of course, by winding the strand when the strand tension is less than the preselected tension and unwinding the strand when the strand tension is greater than the preselected tension.

It should also be understood that the scope of this invention covers the maintenance of strand tensions at fixed tension ratios whether these ratios be equal or differential ratios. The maintenance of ditferential tension ratios may be easily accomplished by varying the length of the lever arm produced by lacing a strand through the surface of revolution. The maintenance of ditferential tension ratios may also be secured by varying the gear ratios of the gear train employed with the surfaces of revolution. Whatever mechanical means are employed, the maintenance of the fixed ratio is obtained by winding a strand having a tension less than that required for the preselected ratio while unwinding a strand having a tension greater than that required for the preselected ratio.

A better understanding of the invention may be had from a discussion of the accompanying drawings in which:

FIGURE 1 is a top view of one form of the tension equalizing device of this invention.

FIGURE 2 is a side view taken along the line II, II of the tension equalizing device of FIGURE 3.

FIGURE 3 is a top view of another form of the tension equalizing device of this invention.

FIGURE 4 is a side view taken along the line IV, IV of the tension equalizing device of FIGURE 3.

FIGURE 5 is a schematic illustration of a tension equalizing device of this invention employed in conjunction with strand plying apparatus.

Turning to FIGURE 1 of the drawings, capstan member I, which is secured to axle member 2, is provided with an orifice 3 which cuts through an upper edge portion of capstan member 1. Capstan member 1 projects from housing cover plate member 4 which, as may be seen in FIGURE 2 of the drawings, is secured to housing member 5. Housing member 5 contains spur gear 6 which is secured to axle 2 by means of set screw 7. Housing cover member 4 has sleeve member 8 secured thereto, sleeve member s carrying an upper ball bearing assembly 9 and a lower ball bearing assembly 18. Upper ball hearing assembly 9 and lower ball bearing assembly 10 assure the ease of rotation of axle 2 which carries capstan member 1 and spur gear 6. When a strand is passed through orifice 3 of capstan 1 in a lacing operation and correspondingly a second strand member passed through orifice member 3' of capstan 1, any tension unbalance existing for instance in the strand passing through orifice 3 of capstan 1 produces a force causing capstan 1 to turn and correspondingly to cause spur gear 6 which is joined to capstan 1 through axle 2 to also turn. The motion of spur gear member 6 is transferred to that spur gear which is joined to capstan member 1' thereby forcing capstan 1 to turn an equal and opposite degree to that amount of motion experienced by capstan member 1. The result, of course, is that any tension unbalance existing between strands passing through orifice 3 of capstan 1 and orifice 3' of capstan 1 are equalized. It is preferred that a damping of the capstan members be achieved by the immersion of spur gear members 6 in a medium viscosity lubricating oil. It should be understood, of course, that other means for damping motion may be employed, in which event the parallel alignment of the axis of rotation of the capstans may be changed, the parallel alignment having been 4. adapted merely to facilitate the use of an oil damping means.

In the event that a yarn plying operation employing in excess of two strands is being conducted or in the event that a tension equalizing device having greater flexibility is desired, the capstans must be coupled through a gear train employing dilferential gears. It should be understood that the number of capstans which may be employed in a gear train using differential gears is not limited. FIG- URE 3 of the drawings is illustrative of the four capstan tension equalizing devices of this invention. In FIGURE 3 capstan member 31 which is secured to axle member 32 is provided with an orifice 33 which cuts through upper edge portion of capstan member 31. Capstan member 31 projects from housing cover plate member 34 which as may be seen in FIGURE 4 of the drawings is secured to housing member 35.

Within housing member 35 are the various components comprising the gear train wherein spur gear 36 is secured to axle 32. Axle 32 is provided with upper ball bearing assembly 38 which is secured between an upper bushing member 39 and a lower bushing member 40. Spur gear 36 which is mounted on axle member 32 by means of ball bearing assembly 41 is rigidly joined to spider member 42. Spider member 42 carries pinion gear 43 which is se cured to spider member 42 by means of ball bearing assembly 44. Pinion gear 43 engages fixed bevel gear 45, fixed bevel gear 45 being rigidly secured to axle member 32 by means of set screw 46. Pinion gear 43 also engages bevel gear 47, bevel gear 47 being free to rotate on axle member 32. Bevel gear 47 is nested within sprocket member 48, sprocket member 48 carrying a ball bearing assembly 49 to permit easy rotation on axle member 32. The lower portion of axle member 32 is supported by means of bracket 50, bracket 50 being secured to housing cover plate member 34 by means of shaft member 51. Bracket member 50 carries ball bearing assembly 52. which facilitates ease of rotation of axle 32. Sprocket member 48 carries chain member 53, chain member 53 engaging sprocket member 54 which is rigidly secured to axle member 55 by means of set screw 56. Axle 55 carries capstan 3 the rotation of capstan 31 on axle 55 being facilitated by means of ball bearing assembly 38' which is secured between upper bushing member 39' and lower bushing member 57. Lower bushing member 57 carries a ball bearing assembly 58 which engages the lower portion of axle 55. Lower bushing member 57 is rigidly secured to housing cover plate member 34 by means of bracket and screw assembly 59.

When a strand is laced through orifice 33 of capstan 31 and, in the event of a tension unbalance, capstan 31 is caused to turn, fixed bevel gear member 45 will also turn. Assuming capstan 31' is laced with a strand passing through orifice 33' of capstan 31' and the tension generated by the strand passing through capstan 31' is less than the tension generated by the strand passing through capstan 31, then sprocket member 54 will exert a force through chain member 53 against sprocket member 48 causing sprocket member 48 to turn. As a result, bevel gear 47 will turn causing pinion gear 43 to turn thereby exerting a torque equalizing force on fixed bevel gear 45. Capstan member 31' will then turn causing the strand passing through orifice 33' to wrap itself about capstan 31' while capstan member 31 also turns causing the strand passing through orifice 33 to unwrap itself from about capstan 31, thereby balancing the strand tensions.

Should yarn passing through orifice 33' of capstan 31 be of a greater tension than yarn passing through orifice 33 of capstan 31 then capstan 31' will be caused to turn so that the strand passing through orifice 33 of capstan 31 will unwrap itself from about capstan 31' while capstan member 31, turns causing the strand passing through orifice 33 to wrap itself about capstan 31, thereby balancing the strand tensions. It should be noted that motion from spur gear member 36 is transmitted to capstan member 31" through corresponding spur gear member 36" and then if capstan member 31" is laced by means of a strand passing through orifice 33" that capstan member 31" when caused to turn will result in the strand passing through orifice 33", wrapping or unwrapping itself as the case may be, about capstan member 31". Similarly capstans 31 or 31'; If the apparatus as illustrated in byv means of the same chain and sprocket member assembly as has previously been described to disclose the linkage existing between capstan member 31 and capstan member 31'.

The tension equalizing apparatus illustrated in FIG- URES 3 and 4 of the drawings may be employed to balance tensions existing between four strands prior to plying operation. However, if so desired the apparatus may be employed to equalize tension existing between three strands or two strands. The apparatus of FIGURES 3 and 4 may be employed to equalize tension existing between three strands by simplying tying down either of capstans 31" or 31'. If the apparatus as illustrated in FIGURES 3 and 4 of the drawings is to be employed to equalize tensions existing between two strands then both capstan members 31 and 31' must be secured in a fixed position. Considering capstan members 31 and 31' to be secured in a fixed position, any torque differential existing between capstans 31 and 31" is controlled by spur gear members 36 and 36", that is to say when both capstan members 31 and 31" are secured in a fixed position the apparatus as illustrated in FIGURES 3 and 4 of the drawings functions exactly the same as the apparatus illustrated in FIGURES 1 and 2 of the drawings.

In operation, as an example, capstans 31, 31" and 31" all rotate in the same direction to unwrap strands therefrom when the tension in the strand about capstan 31 drops. To accomplish this it should be noted that gears 36 and 36- are free to rotate relative to their respective axes 32 in the bearings shown. In other words, when capstan 31 rotates in one direction the other capstan 31 rotates in the opposite direction through sprocket member 54, chain 53, sprocket member 48, and to bevel gear 45 through bevel gear 47 and pinion gear 43. \Bevel gear 45 is fixed to the axle member 32 causing capstan 31 to rotate ina direction opposite to the direction of rotation of capstan 31'. It should be pointed out that pinion gears 43 are rotatably mounted on the spider member 42 and the force of the pinion gear 43 on the bevel gears 45 and 47 will cause spider member 42 to rotate in a horizontal direction since it is rotatably supported on the lower portion of the axle member 32. Therefore, upon rotation of pinion gear 43, spur gear 36 will be rotated by spider member 42 fixed thereto. Rotation of spur gear 36 will rotate spur gear 36" which in turn will rotate spider member 42 rotatably supported on the axle of the capstan 33". Rotation of the spider member of capstan 33" will rotate the pinion gear attached thereto which in turn acts on the bevel gear fixed to the shaft of the capstan 31". Capstan 31" therefore, will rotate in the same direction as capstan 31. Simultaneously, the pinion gear on the spider member of capstan 31" will act on the lower bevel gear to rotate the sprocket member of capstan 31" to rotate capstan 31' in the same direction as capstans 31" and 31 through the chain member and the sprocket fixed to the capstan 31" shaft. Therefore, all three capstans are rotated in the same direction when capstan 31 is rotated in the opposite direction.

The exact way in which the tension equalizing apparatus of this invention is employed as in conjunction with twisting apparatus may be seen in FIGURE 5 of the drawings. In FIGURE 5 the yarns passing from two separate supply packages pass through pigtail guide members 71 and 72. Pigtail guide members 71 and 72 are so positioned so as to present yarn to orifices 73 and 74 of capstans 75 and 76 respectively. In a direction which is perpendicular to the top face of capstan members 75 and 76, the yarns progressing through orifices 73 and 74 of capstans 75 and 76 respectively are wrapped'to a greater or lesser degree about capstan members 75 and 76 depending upon that degree of tension differential existing between the two yarns. The yarns upon having their tensions balanced are then passed over revolving roll member 77 through a common pigtail guide member78 and into ring and traveler twisting apparatus 79. The yarn plying apparatus may, of course, be any of the commercially available types, however, for purposes of this invention yarn plying apparatus such as for instance the yarn plying apparatus described in U.S. Patent No. 2,732,681 has been found to be especially suitable.

Having thus disclosed the invention, what is claimed 1. Apparatus for equalizing strand tensions, said apparatus comprising three or more capstans, each of said capstans being provided with an orifice adapted to receive a strand member in a direction substantially parallel to the axis of rotation of the capstan and eject said strand member in a direction substantially perpendicular to the axis of rotation of said capstan and a mechanical torque transmission means interconnecting and causing, when one of said capstans rotates in one direction due to unbalanced strand tensions, said other capstans to rotate in the other direction to redistribute unbalanced strand tensions.

2. The apparatus of claim 1 wherein said mechanical torque transmission means is composed of spur gears.

3. The apparatus of claim 1 wherein said mechanical torque transmission means contains at least one set of differential gears.

4. The apparatus of claim 1 wherein a damping means is employed in conjunction with said mechanical torque transmission means.

5. Apparatus for equalizing strand tensions, said apparatus comprising two capstans, each of said capstans being provided with an orifice adapted to receive a strand member in a direction substantially parallel to the axis of rotation of the capstan and eject said strand member in a direction substantially perpendicular to the axis of rotation of said capstan and a spur gear train means interconnecting said capstans and causing one of said ca stans to rotate in one direction when the other of said capstans rotates in the other direction due to unbalanced strand tension to redistribute said unbalanced strand tensions.

6. Apparatus for equalizing strand tensions, said apparatus comprising in excess of two capstans, each of said capstans being provided with an orifice adapted to receive a strand member in a direction substantially parallel to the axis of rotation of the capstan and eject said strand member in a direction substantially perpendicular to the axis of rotation of said capstan and a mechanical torque transmission means interconnecting said capstans and. containing sets of dilferential gears equal to the number of capstans minus two to cause, when one of said capstans rotates in one direction due to unbalanced strand tension, said other capstans to rotate in the other direction to redistribute said unbalanced strand tensions.

7. The apparatus of claim 6 wherein said mechanical torque transmission means includes a gear train.

8. A method for plying cord or yarn comprising the steps of: passing one strand around one surface of revolution, passing another strand around a second surface of revolution, rotating one ofi said surfaces of revolution in one direction when the tension in said strands is unbalanced, rotating the other of said surfaces of revolution in a direction opposite to the rotation of the first rotated surface and plying said strands together.

9. The method of claim 8 wherein one of said strands is unwound from its surface of revolution upon rotation while the other of said strands is wound onto its surface of revolution.

10. Apparatus for plying yarn or cord comprising: a plurality of surfaces of revolution, means supplying a strand to each of surfaces in a direction substantially parallel to the axis of rotation of said surface of revolution, mechanical torque transmission means interconnecting said surfaces of revolution to cause, when one of said surfaces of revolution is rotated in one direction due to unbalanced strand tensions, the other of said surfaces of revolution to rotate in the opposite direction to redistribute said unbalanced strand tensions and means plying said strands together.

11. The structure of claim 10 wherein said surfaces of revolution are capstans.

12. The structure of claim 10 wherein said torque transmission means includes a gear train.

References Cited UNITED STATES PATENTS Atwood 242-42 X Grant 242-42 Clarkson 242154 X Busse 242-147 Gerhard 242155 Lenk 24242 FOREIGN PATENTS 15 STANLEY N. GILREATH, Primary Examiner. 

10. APPARATUS FOR PLYING YARN OR CORD COMPRISING: A PLURALITY OF SURFACES OF REVOLUTION, MEANS SUPPLYING A STRAND TO EACH OF SURFACES IN A DIRECTION SUBSTANTIALLY PARALLEL TO THE AXIS OF ROTATION OF SAID SURFACE OF REVOLUTION, MECHANICAL TORQUE TRANSMISSION MEANS INTERCONNECTING SAID SURFACES OF REVOLUTION TO CAUSE, WHEN ONE OF SAID SURFACES OF REVOLUTION IS ROTATED IN ONE DIRECTION DUE TO UNBALANCED STRAND TENSIONS, THE OTHER OF SAID SURFACES 